In the field of wastewater treatment, great efforts are continuously being made to reduce the quantity and concentration of pollutants being discharged into rivers, lakes, surface and ground water supplies, etc. This is evidenced by more and stricter government regulations and requirements relating to wastewater treatment processes and discharges. The quantities of human waste requiring treatment are constantly and rapidly increasing. In the field of potable water purification, available surface and ground water sources are rapidly deteriorating due to pollution caused by contaminated runoff and contaminates generated by a growing population and their careless use of water and improper disposal of waste products.
For example, one area of current concern is the discharge of grey water into the Australian river system. House boats and other marine vessels are commonly used recreational vehicles for families and holiday makers. Under some regulations, grey water can be discharged into the river but some new regulations require appropriate treatment or storage of grey water. Treatment of water for human consumption is also an important area in which the present invention has application. There is also the industrial wastewater industry where wastewater from small industries (such as food processing industries) requires treatment.
The present Applicant is the owner of granted Australian patent 2010291882, incorporated by reference herein, relating to an apparatus and method for the treatment of water that has proven to be successful in the treatment of water and wastewater, including in the abovementioned applications. An exemplary embodiment of such apparatus is shown in FIGS. 1(a) to 1(d) which demonstrates sequential steps of a treatment cycle using the apparatus, referenced by numeral 100.
In the example shown, the apparatus 100 includes a feed pump 102 for transferring, under pressure, water or wastewater via a coagulation coil 104 (to which coagulant and flocculent is added using respective pumps 106 and 108) to a dissolved air flotation (DAF) chamber 110 having a submerged contact chamber 112 and an external pressurised dissolver 114 associated therewith.
The water or wastewater to be treated is pumped into the contact chamber together with air-saturated water from the dissolver 114 (which receives treated water from chamber 110 using recirculation pump 116) which degasses upon entry into the contact chamber 112 and forms bubbles which adhere to suspended matter in the water or wastewater, causing the suspended matter to float to the surface of the chamber. This is shown in FIGS. 1a and 1b. Treated effluent leaves the outlet pipe 118 which has associated therewith an effluent valve 120 which in FIGS. 1a and 1b is open. When valve 120 is closed, the water level in the chamber 110 rises and float material is discharged through the upper discharge line 122 into a waste tank (not shown), as shown in FIG. 1c. The apex shape at the top of the DAF chamber 110 directs float material upwardly into discharge line 122 and then outwardly along an outward extension of the discharge line 122, such flow referred to as a “funneling effect”. When the valve 120 is open again, as shown in FIG. 1d, effluent continues to discharge through outlet pipe 118 and the cycle starts again.
In this example, the outlet pipe 118 causes water to flow into an inlet 124 of outlet pipework 126, wherein the height of the inlet dictates the liquid level in the chamber 110 when the valve 120 is open.
Apparatus such as that shown in FIGS. 1a-1d are adequate for treating wastewater flows up to a certain flowrate. The flow which can be treated is determined by the cross sectional surface area of the chamber 110. When the wastewater flowrate gets too high, the tank geometry requires that the DAF chamber height becomes too high for most practical applications. In addition, by increasing the cross sectional area (and hence the height), the “funneling effect” becomes less efficient as the cross sectional area becomes too large. As such, there is a need for a water or wastewater treatment apparatus capable of handling higher flowrates without necessarily increasing the cross sectional area and the height of the DAF chamber 110.
It is therefore an object of the present invention to overcome at least some of the aforementioned problems or to provide the public with a useful alternative.